Boris Johnson has launched an outspoken personal attack on the David Cameron's handling of the economy, accusing the prime minister of "pussyfooting" around.

In an interview with the Evening Standard on Wednesday, the Tory mayor of London said Cameron needed to immediately approve major building projects in the capital, including new homes and improved rail networks.

He said that it was "totally mad" for the government to delay a decision on whether to expand airport capacity in the South East of England.

"The government needs to stop pussyfooting around. I don’t think you can rely on Heathrow," he said.

Boris enjoyed a high profile during the Olympic Games, and chose a week when the prime minister was on holiday in Spain to make his most striking criticisms of the coalition to date.

His attack on Cameron will be seized upon by those who suspect he is manouvering himself for a return to parliament in order to bid to become the next leader of the Conservative Party.

Speculation will also be fuelled by an Ipsos Mori poll published today, which showed 62% of those surveyed now have a more positive view of the mayor.

Boris has frequently played down or batted away questions as to whether he would like to become an MP again or if he has his sights set on 10 Downing Street.

However asked by the Standard if he would like to move from City Hall to Westminster once his second term as mayor finishes in 2016 he said: “I honestly don’t know the answer to that question.”

On Wednesday a survey by the activist website LabourList suggested that Labour Party supporters thought Boris would be harder to beat in an election than Cameron

According to the poll 51% said Boris would be harder to beat than Cameron with 22% disagreeing.